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coondoggie writes "Princeton University researchers are throwing some cold water on the hot notion that astrobiologists and other scientists expect to one day find life on other planets. Recent discoveries of planets similar to Earth in size and proximity to the planets' respective suns have sparked scientific and public excitement about the possibility of also finding Earth-like life on those worlds, but the expectation that life — from bacteria to sentient beings — has or will develop on other planets as on Earth might be based more on optimism than scientific evidence."

I think Neil DeGrasse Tyson explained it simply, I paraphrase "We are made out of the most common elements in the universe. Only the height of arrogance would say that life couldn't happen anywhere but here". Of course the bigger problem would be that if you actually DID have a race that was able to master space and time what would you talk about? Check out his thoughts here [youtube.com], quite interesting.

"We are made out of the most common elements in the universe. Only the height of arrogance would say that life couldn't happen anywhere but here".

It's not arrogance to say that you should only believe in the existence of something if there's evidence for it.

Otherwise it's just a form of religious faith.

Dr. Tyson isn't saying you should believe that there is any specific life out there. He's saying you shouldn't believe that there is no life out there. Any reasonable, sceptical, person has to acknowledge that there is a reasonable chance that life exists on other planets. Accepting the possibility that other life may actually exist is fundamentally different from firmly believing it exists. To continue you religious analogy: Dr. Tyson seems to be saying we should be extraterrestrial life agnostics unti

And having read the link, I can only say that my own statistical analysis shows with a high degree of confidence that every earth-centric or earth-is-unique argument made so far has been proven wrong. Therefore, expectations that this particular view will endure are probably based on optimism rather than evidence.

Heh. Well, to be fair, that probability is a measurement of what we don't know, not what we do know, so all of the elements used in determining how probable it is that ET life exists ends with something like "hopefully..."

The point I'm getting at is that 'statistical probability' is going to change a LOT once we start getting out there. In that case, it may very well be fair to call that 'optimism'.

Neil DeGrasse Tyson gives a good talk on this, as usual with things related to astrophysics. He points out that the elements we find in our bodies are the same elements you find in the universe, and in the same order (hydrogen is the most common in the universe, and is the most common in us) and that you can trace the atoms in us to the crucible that formed stars. We are, literally, stardust. Well that is almost certainly not a coincidence. We are made of what we are made because the universe is made of what it is made. Same shit with carbon being our building block: Carbon is THE building block, you can make more molecules with it than with all other elements combined.

So looking at all that, we look pretty damn typical, pretty damn common. Thus when you have galaxies with hundreds of billions of stars, and 100-200 billion (observed) galaxies in the universe it becomes a near statistical certainty that such a thing would happen elsewhere. We aren't some special collection of elements that you are highly unlikely to see, we are precisely what you'd expect based on cosmic observation.

But no one knows what the odds are of a getting all the conditions right for life to start.

If you assume that life must be everywhere, then you have to assume that those odds are pretty good.If you assume that life isn't everywhere, then you have to assume that the odds are not very good.

So, In the end that little nugget of information doesn't really help at all. Its just more information that will be viewed through the colored lense of the beholder. In a small kind-of-sort of way, that's what this study is saying.The probability of life existing is determined in a large part by how much researchers assume it to be, rather than on any hard scientific method.

It may be a statistical probability, but scientifically it is actually closer to an impossibility. % of heavy metal stars, that are not binary, have rocky planets, that contain liquid water, and even in the habitable zone of their own galaxies. Which are occupied by beings which: haven't been made yet, haven't gone extinct.
The fact that WE exist at all is the dirty little miracle some scientists admit, but most are embarrassed by for some reason.
Philosophically, this is a wonderful question but
those wh

"The researchers used a Bayesian analysis—which weighs how much of a scientific conclusion stems from actual data and how much comes from the prior assumptions of the scientist—to determine the probability of extraterrestrial life once the influence of these presumptions is minimized."
Source [rdmag.com]

"Our analysis suggests that abiogenesis could be a rather rapid and probable process for other worlds, but it also cannot rule out at high confidence that abiogenesis is a rare, improbable event," Spiegel said. "We really have no idea, even to within orders of magnitude, how probable abiogenesis is, and we show that no evidence exists to substantially change that."..also...

"It could easily be that life came about on Earth one way, but came about on other planets in other ways,

Various chemistry teachers have said that. Carbon atoms have an unusual ability at linking together in various ways to form large, complex, molecules. Silicon, e.g., just isn't in it. (Not that silicon is an impossibility at considerably higher temperatures, but it would also require a considerably stronger gravity, as it needs to work through silicones rather than via Si-Si linkages.)

IOW, Carbon based life has lots of advantages, and it more likely in more environments than other possibilities. It is t

Which means nothing. The primary focus of the argument was more specifically the fact that just because life here started so quickly doesn't mean its a good expectation that life occurred as quickly anywhere life is supportable in the universe. Perhaps we were a statistical outlier and we had life appear far faster than the average. The fact is we just don't know, but because we don't know we can't make the assumption that life is on every earth-like planet.

Just as we can't make the assumption that life is on every non-earth-like planet. In fact making any assumption about extraterrestrial life whatever is pretty silly and certainly not science. More philosophy or religion than science. Perhaps a few hundred thousand years after we develop a practical interstellar space drive we will have some evidence upon which to base a conclusion. Until then the most scientific thing one can do in response to the question of life on other planets is to STFU. Which, for som

Garbage in garbage out. There is currently insufficient data upon which to base any sort of 'estimate'. There is currently no way to know how many earth-like worlds there are in the galaxy. It certainly seems likely that the number of earth-like worlds in any galaxy would be a non-zero number, but currently all we can do is speculate wildly. So far we haven't found even one other earth-like world. All we have found is that there seem to be a large variety of planets orbiting many, perhaps most, stars at a large variety of orbital distances, including some in the goldilocks zones. Now we have some evidence from which we can conclude that planets are relatively common, but we simply cannot say how common earth-like water planets are.

"The researchers used a Bayesian analysis—which weighs how much of a scientific conclusion stems from actual data and how much comes from the prior assumptions of the scientist—to determine the probability of extraterrestrial life once the influence of these presumptions is minimized."Source [rdmag.com]

Which amounts to, "my filter hasn't found any papers on extra-terrestrial life we've found yet, so clearly no evidence of extra-terrestrial life exists." I don't need a Bayesian filter to figure that one out, and it's actually pretty stupid to use one. We already know that we haven't found any life outside the Earth.

That said, the existence of life on Earth is all the evidence you need for life elsewhere. The chance of life arising is bigger than zero, and the amount of planets is large enough that for anything with probability not zero, it's going to happen more than once. The only valid question is just how full of life is the universe? Is it mostly lifeless or chock-full of it?

If you are willing to stipulate that God exists this actually makes for an awesome thought experiment.Would God, being omnipotent and omnipresent want multiple worlds of beings?What if he was curious* as to silicon based life, that would appear to be incompatible with a world configured for carbon life, so he would need to spin up another world.What if God wanted a world of fire to play with creatures for whom consciousness existed in the flickering of flames?There appears to be no reason why he wouldn't want other worlds, of course there is also no reason why he would either.

Imagine the possibilities, something akin to the final scene of MiB where the galaxy is really in a marble being played with, maybe there are other marbles?

Whether or not you choose to believe is a decision only you can make, doesn't mean you can't have fun with various viewpoints. That said, I think the God talk on/. is the new troll. Guaranteed to get a response every time;)-nB

* Of course being omnipotent means there is no curiosity, as God already knows everything... Thus why bother with the first world (assuming that's us) in the first place?

"Is God willing to prevent evil, but not able?
Then he is not omnipotent.
Is he able, but not willing?
Then he is malevolent.
Is he both able and willing?
Then whence cometh evil?
Is he neither able nor willing?
Then why call him God?"

Reading the bible, it's clear that God is deeply insecure and has about the emotional maturity of a two year old right through the old testament. In the new testament he gets laid and turns into a hippy.

Not only do you have a god given free will but you are allowed to have questions even if you were a person of faith. How many religions allow people to have doubts? How many religions allow people to question what is taught? A faith is not worth anything if it cannot stand up to questions.

So, given the history of every single religion, you basically state outright that no faith is worth anything.

There is not a single semi-organized religion or faith, that did not at one point or another declare people with doubts (or simply people who were in the way, politically, militarily or socially) as heretics of one form or another. The Catholics had the Jews, Albigensian, Protestants, Orthodox, Muslims, African/American natives etc. pp. Those each in turn had others they at some point persecuted with

If "he" were "real", he'd have more problems than that. Just imagine what would cause an omnipotent intelligence to have that kind of raving paranoia.

FWIW, I'm quite convinced that gods are real, but also that their reality is as a kind of mental sublayer roughly analogous to Jungian archetypes. Think of them as the microcoding of the minds, not only of humans, but of at least all mammals. Occasionally we externalize these mental processes, and they can be *extremely* impressive. But don't expect them t

In My Father's house are many dwelling places; if it were not so, I would have told you; for I go to prepare a place for you. - Johm 14:2

The usual interpretation of this has to do with Heaven, but who knows? It could mean that we are meant to 'go forth and multiply' and populate the universe. It's just possible that we are the first, the only, and have the potential to propagate Life from its only original source. Maybe that is our calling - to seed Life everywhere. Truly, if/when we do move into space, we will be bringing many other forms of life with us - a significant part of our entire ecosystem.

In all seriousness, we haven't even got a foot on the next planet over. I think we can afford to not bicker and argue over the prospects for life elsewhere for a bit. Give science a chance to discover what it will.

By all counts, maths, physics, biology, chemistry, there is life anywhere else outside of Earth, period. Unless we really are in a magical fantasy world made by some bored deity playing Sims Universe.

Life develops easily with the right requirements, we know this from quite a lot of evidence. We even recreated genesis by accident, twice, and once on purpose just recently.We see evolution right in front of us every day, and can even tweak it. We have been doing so for

"Life develops easily with the right requirements, we know this from quite a lot of evidence. We even recreated genesis by accident, twice, and once on purpose just recently."

Really? Can you provide a link? I've not heard this. I've heard that we've created environments SIMILAR to early earth -- and basic proteins developed... the BUILDING BLOCKS of life. But I haven't heard anything about creating life.

I heard the story before, and believe it to be pure BS. Some guy claims to have made his own primordial soup by sloshing around chemicals. There was no Science I could find to back his claim. It was some anti-creationist on Youtube, but I can't remember the name.

Because if life doesn't look like us, there's no point in finding it. Seriously, do you want to have a hot makeout session with a 5-limbed cross between a cockroach and a slime mold from Rigel 7 No, of COURSE you don't.

You'd much rather do a little heavy petting with a light-green hottie with blonde hair and 4 boobs from Proxima Centauri. If Star Trek (and the Secret Service) have taught us anything, it's that getting it on with hot chicks in other places is pretty much the only reason to explore.

The physical differences between Asian, Aferican and European decendents exist because of the time it took for our species to propogate around the world, isolation, enviornmental factors, boarders, politics, and the slow speed of travel at the time.

In the forseable future, humanity may spread to other planets via generation ships with pressures not unlike those faced by our genetic ancestors. The limited communication between colonies, limited travel opportunities, and enviornmental pressures between habited planets will probably mean that humans on distant stars will begin to take on traits that are very different than those of us who live on earth.

It's entirely plausable, and even likely, that as humanity spreads around the stars, we will evolve into something not unlike the aliens of star trek. In the future, there just might be a green woman out there waiting for you - someone Alian, but also someone human.

There are those who believe that life here began out there, far across the universe, with tribes of humans who may have been the forefathers of the Egyptians, or the Toltecs, or the Mayans. That they may have been the architects of the great pyramids, or the lost civilizations of Lemuria or Atlantis. Some believe that there may yet be brothers of man who even now fight to survive somewhere beyond the heavens.

Because meat tastes much better when it has been properly aged before cooking. Anyway, humans are full of saturated fats and artificial additives.

But seriously folks - its easy to speculate about forms of "life" beyond our imagination, but if you're talking about trying to find life on exoplanets simply by estimating their surface conditions or maybe, if you are lucky, a bit of spectroscopic data about the atmosphere then the only signs you could look for are the ones you know to be associated with "life

You seem to be assuming that SETI is expecting to find radio leakage from other worlds. That simply is not the case. SETI is based upon the idea of civilizations who might choose to attempt to communicate intentionally either with the entire galaxy using some method quite similar to pulsars or via an automated EM beam that settles on a star system for some period of time before moving on to another. Either way whatever technology they use to communicate with each other on their own planet doesn't factor int

This is a case where the statement "absence of evidence is not evidence of absence." Yes, we have no evidence as of yet, but at the same time we have a sample size of exactly one, so trying to making any claim on the frequency or infrequency of life elsewhere in the Universe is utterly ludicrous.

It is, indeed, quite likely that we are unique. This isn't an argument that life doesn't exist elsewhere, just that it will be different. And we can't readily put bounds around how different. (Though I believe that carbon based life will be overwhelmingly dominant. But I'm less certain about liquid water. We really need to take a better look at Titan before I commit myself. It seems quite plausible that low gravity worlds with ammonia or methane based chemistries would be more common than earthlike wor

I think we are at a point where most adults have grown up their entire lives with the assumption that certain great discoveries and advancements will be made in their lifetime. Moon bases. Mars missions. Evidence (at least) of extra-terrestrial life. As these folks (I am one of them) hit the downward slope of their life expectancy (which itself hasn't seen the expected advancements), I expect much more wild speculation, straw-grasping and fallacious conclusions about what "must" exist.

If the universe is so immense that it is unlikely that extra-terrestrial life doesn't exist, then it is immense enough that we will probably never find it. Then there is the whole issue of whether that life evolved and died a billion years in the past.

Meanwhile, there are plenty of real problems to be solved and discoveries to be made here on Earth, if anyone is still interested.

We really don't know what the odds are for life evolving, nor the factors that make it more or less likely except on the grossest scale. But as another post, not yet modded up still at 0 points out, the current lack of evidence for life is not evidence of lack of life.

Princeton University researchers are [speculating] on the [speculation] that astrobiologists and other scientists [speculate] to one day find life on other planets. Recent discoveries [...] have sparked [speculation] about the possibility of also finding Earth-like life on those worlds, but the [speculation] that life - from bacteria to sentient beings - has or will develop on other planets as on Earth might be based more on [speculation].

Nothing new here. Just the same old complaint of cognitive bias due to our desire to find someone else.
Which does not change the fact that life, and even intelligent life are verifiable possibilities in the universe: we do exist, so the process can be repeated somewhere else.
Unless you give up on the mediocrity principle and accept that Earth is special. Which from a scientific point of view increasingly seems not to be the case (with all the other confirmed extrasolar planets, some in the Goldilocks zone

The uncertainties are so large around life that currently noone can call "we will find life for sure" whimsical or optimistic compared to "we won't find life elsewhere for sure". It's just as uncertain.

This guy is an astrophysicist, not an astrobiologist. Don't trust a chemist to talk about physics, you don't trust a geologist about climate science, and you don't trust a astrophysicist to talk about biology.

This is once again more moronic bullcrap that says other planets are not like earth, so life can't evolve on them.

Most of the universe is composed of dark matter. We know nothing about dark matter, so saying you won't find life there is like saying you don't think there is any thing in a closed bo

This guy is an astrophysicist, not an astrobiologist. Don't trust a chemist to talk about physics, you don't trust a geologist about climate science, and you don't trust a astrophysicist to talk about biology.

He could be a janitor for all I care. The only important question is: is his science sound or not.

The idea of finding life on other planets is actually based on statistics. There are literally billions of Earth-like planets in the universe. The chances are that conditions on at least some of those planets has given rise to life.

There is also a very good statistical chance that there are non-carbon life-forms on other planets.

So unless you've got a "God created the Earth" mentality, there being life on other planets is a foregone conclusion.

Does that mean we'll encounter life from other planets? Perhaps not. That depends on whether any forms of FTL ever prove feasible, beyond which there's the roll of the dice of the rarity of planets with life. The odds are you'd have visit and explore a fair number of dead worlds before you'd encounter one with life.

Only those who think we are "created in God's image" would stick their heads in the sand and claim otherwise. God has no image, and it's form is the universe itself. To think we look anything like the universe is ludicrous!

The idea of finding life on other planets is actually based on statistics. There are literally billions of Earth-like planets in the universe. The chances are that conditions on at least some of those planets has given rise to life.

And what, if I may be so crass as to inquire, do you base that assessment on? The fact that "billions" is a large-seeming number? What if the probability of life (as we know it) forming on an earth-like planet is 1:10^12? The point of the article is that we simply don't know what that probability is, so arguments like the one you are making here are based on fantasy rather than evidence.

There is also a very good statistical chance that there are non-carbon life-forms on other planets.

Again: How do you know? Before, you were making a statistical argument from a sample size of one, which is bad. But now, since we know of zero planets that host non-carbon-based life, you are making an argument based on literally nothing but maybe old Star Trek episodes.

And what, if I may be so crass as to inquire, do you base that assessment on? The fact that "billions" is a large-seeming number? What if the probability of life (as we know it) forming on an earth-like planet is 1:10^12? The point of the article is that we simply don't know what that probability is, so arguments like the one you are making here are based on fantasy rather than evidence.

What is more unlikely, that Earth is the special seed in the hundreds of billions of galaxies out there, all composed of a few billions stars each, or that we're just one of many such planets carrying life. Now, as the previous poster said, that doesn't mean we're ever going to encounter said life, but it is a HELL of an assumption that the qualities for production of life are so remote that only Earth managed to fit the criteria, especially when the biological evidence so far speaks to life being surprisi

I like to think that "in God's image" refers not to the physical. I'm going to borrow a bit from Neitzche here.

Companions the creator seeks, not corpses, not herds and believers. Fellow creators the creator seeks--those who write new values on new tablets. Companions the creator seeks, and fellow harvesters; for everything about him is ripe for the harvest.

Don't worry, some of us who believe in some sort of God also believe that we have brains and logic for a reason. And that any human attempt to simp

Sure, why not? Let's see, if an alien civilization discovered how to travel at the speed of light, and they lived in the nearest solar system with earth-like planets, then it's only 44 trillion kilometers or 4.4 light years away. I can see traveling for 4.4 years in a small spacecraft in order to pick up farmers and mechanics on earth and probe them.

--
No chance, English bed-wetting types. I burst my pimples at you and call your door-opening request a silly thing, you tiny-brained wipers of other people

I thought science was about forming a theory or hypothesis and then either proving or disproving it. You can't see gravity but it's there, Isaac Newton didn't discover it, but he started pondering the mechanism. Does not mean that the billions of years prior to that everything floated.

I think if anything it will make us redefine what is life, not to mention that it's going to be hard to prove or disprove life on other planets without evidence to support or lack or evidence to refute it, just because we don

the problem that NASA etc. isn't really considering is that some of the planets they're looking at could well have had life borne out of the primordal soup, evolved to sentience, discovered genetic engineering, created plants and food crops that went out-of-control and destroyed the entire ecology and turned the entire planet into a barren wasteland... all hundreds of millions of years before NASA or anyone else took a peek at the barren rock that is left from a distance of billions of miles away.

Because even if there's some non zero probability of existing, people of earth will never ever ever ever ever ever ever ever ever find it. Never. Not ever. Mankind will never find any direct evidence of life anywhere else.

Life arose on Earth sometime in the first few hundred million years after the young planet had cooled to the point that it could support water-based organisms on its surface. The early emergence of life on Earth has been taken as evidence that the probability of abiogenesis is high, if starting from young Earth-like conditions. We revisit this argument quantitatively in a Bayesian statistical framework. By constructing a simple model of the probability of abiogenesis, we calculate a Bayesian estimate of its posterior probability, given the data that life emerged fairly early in Earth’s history and that, billions of years later, curious creatures noted this fact and considered its implications. We find that, given only this very limited empirical information, the choice of Bayesian prior for the abiogenesis probability parameter has a dominant influence on the computed posterior probability. Although terrestrial life's early emergence provides evidence that life might be abundant in the universe if early-Earth-like conditions are common, the evidence is inconclusive and indeed is consistent with an arbitrarily low intrinsic probability of abiogenesis for plausible uninformative priors. Finding a single case of life arising independently of our lineage (on Earth, elsewhere in the solar system, or on an extrasolar planet) would provide much stronger evidence that abiogenesis is not extremely rare in the universe.

Recent discoveries of planets similar to Earth in size and proximity to the planets' respective suns have sparked scientific and public excitement about the possibility of also finding Earth-like life on those worlds.

But Princeton University researchers have found that the expectation that life---from bacteria to sentient beings---has or will develop on other planets as on Earth might be based more on optimism than scientific evidence.

Wow, this sounds like just what scientists were saying about the likelihood of discovering extrasolar planets themselves... before a bunch were discovered. And then I remember a flurry of stories full of similar nay-saying, but just about the idea of discovering Earth-sized planets. Until they discovered some of those, too.

The title is completely wrong. Nothing about this work suggests extraterrestrial life isn't plausible, nor that there's anything whimsical about it. Here is what they actually said.

We know that life appeared on earth very soon after the surface became cool enough to be habitable. People therefore assume the same would be true on other planets. But having only one data point doesn't give us enough evidence to actually conclude that with any confidence. In particular:

1. It took a few billion years after that for life to evolve to the point where it could wonder about the possibility of life on other planets.2. If it had taken a few billion years for life to appear in the first place, we might never have reached this point.3. Therefore this might just be an anthropic effect. Intelligent life forms will always find themselves on planets where life appeared quickly, but that doesn't tell you how often life actually does appear quickly.

Thousands of Exo-planets discovered. Viking’s life detection experiments are being reconsidered. Life has been found to have started very early in Earth’s evolution. Various Extremophiles discovered. For the last twenty years the evidence keeps tipping in favor of extraterrestrial life being more and more likely. That we haven’t yet discovered said life says more about our commitment to doing so than its likely-hood.

Sadly this article will be linked to a thousand times by the ID crowd shouting we need to stop wasting all this money looking for ET and realize how special and God chosen we are.

I’d also add Bayesian analysis sucks when it comes to these all or nothing analysis with such a small sample size. Bayesian analysis can be used to say we have approximately 50-100 years of civilization left. HOWEVER the same analysis 200 years ago would have given roughly the same result. These kinds of statistics mean nothing until you have a large data set that is properly categorized. We don’t even know for certainty our next nearest planetary neighbor is lifeless. Finding life on Mars would sudden explode Bayesian stats to near certainty that life is everywhere.

There is no support either for or against the existence of life on other planets. Bayesian analysis doesn't transform that lack of knowledge into evidence against life. After Bayesian analysis, people still don't have any facts.

However, I'd say things certainly look better now than they did a few decades ago, given that we have discovered both vast amounts of organic molecules in space, as well as lots of planets in the Goldilocks zone.

Did life come about because of a confluence of circumstances unique to Earth or can it develop and thrive with a fairly broad set of conditions?

That's the fundamental question, because there are a variety of conditions on Earth that are relatively unique. But did live develop here specifically because of those conditions or was it only shaped because of them? I mean, if you examine life everything fits just right but what we have is a chicken and egg scenario.

Keep in mind that if life were as resilient and adaptable that we should be finding evidence of it surviving elsewhere within our own solar system. So far we haven't found anything which would imply that specific conditions are required. But how specific are the requirements. Earth isn't tidal locked, we've got a large satellite and a fairly stable star, plate tectonics, amongst countless other things. So who knows what the real odds are. I will concede, however, that it's far from being too late to find something on a neighboring planet.

I do like being optimistic about this, however, so I want to believe that life should be common. However, given the vastness of the universe "common" is an extremely relative term. What are the odds of finding complex multi-cellular life within a distance we can realistically travel? And what are the odds of finding life that is thriving within our time frame. Chances are that most life gets snuffed out long before it's able to evolve into anything noteworthy.

We have buildings of steel and glasswe have put men on the moonWe have a machine on the cusp of leaving the solar systemwe have mapped millions of other planetsWe can travel faster the soundWe can talk across the globe in an instant